Hertzsprung-Russell diagram

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Criado para o OAE

Legenda: This diagram shows the temperature and luminosity of different stars. The size of each point represents the star’s radius and its colour is the colour the human eye would see. The stars range in colour from a washed-out blue to a washed-out reddish-orange. No star has a pure colour like red, green or blue as stars’ spectra include light from lots of different colours. However the reddest stars are commonly referred to as red and the bluest stars as blue. The sample of stars used to make this diagram was chosen to show a wide range of stars of different types so the relative number of each type of star is not representative of how commonly each type is found. From the top left to bottom right there is a long line of stars burning hydrogen in their cores. This is called the main sequence. On this line, one sees the stars Mintaka, Achernar, Sirius A, the Sun and Proxima Centauri. The objects around Proxima Centauri at the lower right end of the main sequence are known as red dwarfs. To the lower right of the red dwarfs are Teide 1 and Kelu-1 A. These two objects are brown dwarfs, objects too low in mass to have cores hot enough to fuse hydrogen for a sustained period of time. As they do not burn hydrogen, brown dwarfs are not considered main sequence stars. The name brown dwarf is unrelated to their colour. Above the main sequence, we find subgiants, giants and supergiants. These are stars that have finished burning hydrogen in their core and have evolved into larger objects. A star’s brightness depends on its temperature and size so giant stars are brighter than stars with a smaller radius but the same temperature. In time these objects will move towards the end of their lives and undergo either a planetary nebula phase or become supernovae. Stars which end their lives with a planetary nebula phase become a type of stellar remnant called a white dwarf. Such objects are much smaller than stars of the same temperature and thus are fainter and are found significantly below the main sequence. Stars which end their lives as supernovae become either black holes or neutron stars. These are not shown on this plot.
Crédito: IAU OAE/Niall Deacon

Termos do Glossário: Anã marrom , Cor , Estrela gigante , Diagrama de Hertzsprung–Russell (HR) , Luminosidade , Sequência Principal , Evolução estelar , Estrela supergigante , Anã Branca , Temperatura efetiva , Estrela subgigante , Classe de luminosidade
Categorias Estrelas

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Cygnus Constellation Map

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Legenda: The constellation Cygnus with its bright stars and surrounding constellations. Cygnus is surrounded by (going clockwise from the top): Cepheus, Draco, Lyra, Vulpecula, Pegasus and Lacerta. Cygnus is notable for its brightest star Deneb. This forms one vertex of the prominent Summer Triangle asterism that is visible in northern hemisphere summer evenings. Cygnus is a northern constellation and thus the whole of the constellation is visible at some point in the year in the whole northern hemisphere. The whole constellation is also visible from equatorial regions of the southern hemisphere with parts of the constellation visible from temperate southern regions. The plane of the Milky Way runs through Cygnus and thus the constellation is rich in nebulae and star clusters. These include the North America Nebula (NGC 7000) and the Crescent Nebula (NGC 6888). The Veil Nebula is a huge supernova remnant, parts of which are marked here as NGC 6960 and NGC 6992/5. All of the previously-mentioned nebulae are marked with green squares. The planetary nebula NGC 6826 is marked here with a green circle superimposed on a plus sign. The open star clusters M29 and M39 are marked here with yellow circles. The y-axis of this diagram is in degrees of declination with north as up and the x-axis is in hours of right ascension with east to the left. The sizes of the stars marked here relate to the star's apparent magnitude, a measure of its apparent brightness. The larger dots represent brighter stars. The Greek letters mark the brightest stars in the constellation. These are ranked by brightness with the brightest star being labeled alpha, the second brightest beta, etc., although this ordering is not always followed exactly. The dotted boundary lines mark the IAU's boundaries of the constellations and the solid green lines mark one of the common forms used to represent the figures of the constellations. Neither the constellation boundaries, nor the lines joining the stars appear on the sky.
Crédito: Adapted by the IAU Office of Astronomy for Education from the original by the IAU and Sky & Telescope
Link do crédito

Termos do Glossário: Magnitude aparente , Coordenadas celestes , Constelação , Declinação , Via Láctea , Nebulosa , Nebulosa Planetária , Ascensão Reta (AR) , Asterismo , Aglomerado aberto , Remanescente de supernova
Categorias Astronomia a Olho Nu

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Vulpecula Constellation Map

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Legenda: The constellation Vulpecula with its brighter stars and surrounding constellations. Vulpecula is surrounded by (going clockwise from the top): Cygnus, Lyra, Hercules, Sagitta, Delphinus and Pegasus. Vulpecula is a northern constellation and thus the whole constellation is visible at some point in the year throughout the northern hemisphere. The whole constellation is also visible in equatorial and temperate regions of the southern hemisphere. Vulpecula is best viewed in the evening in the northern hemisphere early autumn and southern hemisphere early spring. The planetary nebula M27, commonly known as the Dumbbell Nebula lies in Vulpecula and is marked here with a green cross superimposed on a plus sign. The open cluster NGC 6885 also lies in Vulpecula and is marked here with a yellow circle. The y-axis of this diagram is in degrees of declination with north as up and the x-axis is in hours of right ascension with east to the left. The sizes of the stars marked here relate to the star's apparent magnitude, a measure of its apparent brightness. The larger dots represent brighter stars. The Greek letters mark the brightest stars in the constellation. These are ranked by brightness with the brightest star being labeled alpha, the second brightest beta, etc., although this ordering is not always followed exactly. The dotted boundary lines mark the IAU's boundaries of the constellations and the solid green lines mark one of the common forms used to represent the figures of the constellations. Neither the constellation boundaries, nor the lines joining the stars appear on the sky.
Crédito: Adapted by the IAU Office of Astronomy for Education from the original by the IAU and Sky & Telescope
Link do crédito

Termos do Glossário: Magnitude aparente , Coordenadas celestes , Constelação , Declinação , Nebulosa Planetária , Ascensão Reta (AR) , Aglomerado aberto
Categorias Astronomia a Olho Nu

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Aquarius Constellation Map

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Legenda: The constellation Aquarius along with its bright stars and surrounding constellations. Aquarius is surrounded by (going clockwise from the top) Pegasus, Equuleus, Aquila, Capricornus, Piscis Austrinus, Sculptor, Cetus and Pisces. Aquarius lies on the ecliptic (shown here as a blue line), this is the path the Sun appears to take across the sky over the course of a year. The Sun is in Aquarius from mid February to mid March. The other planets of the Solar System can often be found in Aquarius. Aquarius spans the celestial equator and is thus visible at some time in the year from all of planet Earth. In the most arctic or antarctic regions of the world, some parts of the constellation may not be visible. Aquarius is most visible in the evenings in the northern hemisphere autumn and southern hemisphere spring. The yellow circles with plus symbols superimposed on them mark the globular clusters M2 and M72. The green circles superimposed on plus symbols mark the planetary nebulae NGC 7293 (the Helix Nebula) and NGC 7002 (the Saturn Nebula). M73 (marked with an x symbol) is a coincident grouping of stars previously erroneously classified as an open cluster. The y-axis of this diagram is in degrees of declination with north as up and the x-axis is in hours of right ascension with east to the left. The sizes of the stars marked here relate to the star's apparent magnitude, a measure of its apparent brightness. The larger dots represent brighter stars. The Greek letters mark the brightest stars in the constellation. These are ranked by brightness with the brightest star being labeled alpha, the second brightest beta, etc., although this ordering is not always followed exactly. The dotted boundary lines mark the IAU's boundaries of the constellations and the solid green lines mark one of the common forms used to represent the figures of the constellations. Neither the constellation boundaries, nor the line marking the ecliptic, nor the lines joining the stars appear on the sky.
Crédito: Adapted by the IAU Office of Astronomy for Education from the original by IAU/Sky & Telescope
Link do crédito

Termos do Glossário: Magnitude aparente , Capricórnio , Coordenadas celestes , Constelação , Declinação , Eclíptica , Aglomerado Globular , Peixes , Nebulosa Planetária , Ascensão Reta (AR) , Zodíaco , Aquário , Aglomerado aberto
Categorias Astronomia a Olho Nu

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Draco Constellation Map

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Legenda: The constellation Draco with its bright stars and surrounding constellations. Draco is surrounded by (going clockwise from the top): Cepheus, Ursa Minor, Boötes, Hercules, Lyra and Cygnus. Draco is a sprawling northern constellation, parts of which lie close to the celestial north pole. As such the whole constellation is visible at some point in the year from the whole northern hemisphere and a thin sliver of the southern hemisphere near the equator. Parts of the constellation are visible from all other southern equatorial and some southern temperate regions. Draco is best viewed in the evenings in the northern hemisphere summer and southern hemisphere winter. The planetary nebula NGC 6543 (also known as the Cat’s Eye Nebula) lies in Draco. It is marked here with a green circle superimposed on a plus sign. This diagram maps an area around the north celestial pole. Here lines of constant right ascension converge. The right ascension values of these lines are marked on the x-axis above and below the diagram. Some of the lines of constant declination are marked on the y-axis. The sizes of the stars marked here relate to the star's apparent magnitude, a measure of its apparent brightness. The larger dots represent brighter stars. The Greek letters mark the brightest stars in the constellation. These are ranked by brightness with the brightest star being labeled alpha, the second brightest beta, etc., although this ordering is not always followed exactly. The dotted boundary lines mark the IAU's boundaries of the constellations and the solid green lines mark one of the common forms used to represent the figures of the constellations. Neither the constellation boundaries, nor the lines joining the stars appear on the sky.
Crédito: Adapted by the IAU Office of Astronomy for Education from the original by the IAU and Sky & Telescope
Link do crédito

Termos do Glossário: Magnitude aparente , Coordenadas celestes , Estrelas circumpolares , Constelação , Declinação , Polo Celeste Norte (PCN) , Nebulosa Planetária , Ascensão Reta (AR)
Categorias Astronomia a Olho Nu

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